Treatment studies have shown pre to post changes in reading circuits with evidence based remediation of reading disability, establishing the neural signature of successful treatment outcome. However, insight into the neurobiological mechanisms by which treatment produces these consequences/outcome requires monitoring modulations of key brain regions throughout the course of treatment and such data are lacking. Moreover, in any cohort some RD children with highly similar profiles on standardized testing at the beginning of intervention will show large gains and others will not. In the current proposal children with reading difficulties will be followed through an evidence-based training program focused on learning print-sound relationships with progressive emphasis at three grain sizes (grapheme-to-phoneme (GP), body/rime, and morphological) and the school-based small group instruction will be supplemented by online practice to reinforce training with an evidence-based computer assisted reading instruction (CARI). Cognitive testing and functional neuroimaging (before and after the intervention) with comparisons to untreated RD and TD control groups will allow for the identification of key neurocognitive factors associated with response to treatment. Eight recordings of brain activity using functional Near-Infrared Spectroscopy (fNIRS) imaging throughout the 20 weeks of instruction will be used to identify how online modulation of circuits during treatment relates to weekly measures of reading performance - growth spurts (or regressions) over the course of treatment. This dynamic tracking study will yield new insights into how evidence-based training modulates brain organization for learning to support reading gains and why it fails to do so for some children. Specific Aims are: 1) To examine the pre to post training changes in print and speech activation and functional connectivity in relation to variable treatment responses. 2) To track dynamic adaptive changes in activation and functional connectivity during treatment that predict local growth spurts and outcomes in RD. Aim 3) To examine neurocognitive changes associated with training on progressively larger grain-size units during treatment (GP, body/rime, morphological) and how these patterns are qualified by individual differences in pre-treatment profiles.